Method for transmitting/receiving signal and device therefor

ABSTRACT

The present invention relates to a wireless communication system. More particularly, the present invention relates to a method comprising: setting a first cell having a first TDD UL-DL configuration and a second cell having a second TDD UL-DL configuration; receiving a PHICH signal in a subframe #(n−L) of the first cell, or receiving a PDCCH signal in a subframe #(n−K) of the first cell; and transmitting a PUSCH signal in a subframe #n of the second cell, corresponding to the PHICH signal or the PDCCH signal, wherein the relationship between the subframes #(n−L), #(n−K), and #n is determined in consideration of a parameter value set in a specific TDD UL-DL configuration, which is the TDD UL-DL configuration having the least number of UL subframes from TDD UL-DL configuration(s), in which subframes set as UL in the first or second cell are all set as ULs.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore specifically, to a method for transmitting/receiving a signal in amulticarrier system supporting TDD (Time Division Duplex) and a devicefor the same.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services including voice and dataservices. In general, a wireless communication system is a multipleaccess system that supports communication among multiple users bysharing available system resources (e.g. bandwidth, transmit power,etc.) among the multiple users. The multiple access system may adopt amultiple access scheme such as Code Division Multiple Access (CDMA),Frequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or SingleCarrier Frequency Division Multiple Access (SC-FDMA).

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method for efficiently transmitting/receiving a signal in a wirelesscommunication system and a device for the same. Another object of thepresent invention is to provide a method for efficientlytransmitting/receiving a signal in a multicarrier system supporting TDDand a device for the same. Another object of the present invention is toprovide a method for reusing existing signal transmission/receptiontiming when signal transmission and reception timing is configured in amulticarrier system supporting TDD and a device for the same.

The technical problems solved by the present invention are not limitedto the above technical problems and those skilled in the art mayunderstand other technical problems from the following description.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting an uplink signal in a wireless communicationsystem supporting carrier aggregation, the method including: configuringa first cell having a first TDD (Time Division Duplex) UL-DL(Uplink-Downlink) configuration and a second cell having a second TDDUL-DL configuration; receiving a PHICH (Physical HARQ Indicator Channel)signal in a subframe #(n−L) of the first cell or a PDCCH (PhysicalDownlink Control Channel) signal in a subframe #(n−K) of the first cell;and transmitting a PUSCH (Physical Uplink Shared Channel) signal in asubframe #n of the second cell, corresponding to the PHICH signal or thePDCCH signal, wherein the relationship among the subframes #(n−L),#(n−K) and #n is determined in consideration of a parameter value set ina specific TDD UL-DL configuration included in a TDD UL-DL configurationset, wherein the specific TDD UL-DL configuration corresponds to a TDDUL-DL configuration having a smallest number of UL subframes among oneor more TDD UL-DL configurations in which one or more subframesconfigured as UL in the first cell or the second cell are all configuredas UL, wherein, when the second cell is configured as UL, in a ULsubframe (UU) located prior to the subframe #n according to the specificUL-DL configuration, the subframe #(n−L) is determined according to aparameter set to the UL subframe (UU), wherein, when the second cell isnot set to UL in the UL subframe (UU), the subframe #(n−L) is determinedaccording to a parameter value applied to a UL subframe prior to thesubframe #n in the second cell, n is an integer greater than 0, and Kand L are respectively integers equal to or greater than 1.

In another aspect of the present invention, provided herein is acommunication device A communication device configured to transmit anuplink signal in a wireless communication system supporting carrieraggregation, the communication device including a radio frequency (RF)unit and a processor, wherein the processor is configured to configure afirst cell having a first TDD UL-DL configuration and a second cellhaving a second TDD UL-DL configuration, to receive a PHICH signal in asubframe #(n−L) of the first cell or a PDCCH signal in a subframe #(n−K)of the first cell, and to transmit a PUSCH signal in a subframe #n ofthe second cell, corresponding to the PHICH signal or the PDCCH signal,wherein the relationship among the subframes #(n−L), #(n−K) and #n isdetermined in consideration of a parameter value set in a specific TDDUL-DL configuration included in a TDD UL-DL configuration set, whereinthe specific TDD UL-DL configuration corresponds to a TDD UL-DLconfiguration having a smallest number of UL subframes among one or moreTDD UL-DL configurations in which one or more subframes configured as ULin the first cell or the second cell are all configured as UL, wherein,when the second cell is configured as UL, located prior to the subframe#n in a UL subframe (UU) according to the specific UL-DL configuration,the subframe #(n−L) is determined according to a parameter set to the ULsubframe (UU), wherein, when the second cell is not set to UL in the ULsubframe (UU), the subframe #(n−L) is determined according to aparameter value applied to a UL subframe prior to the subframe #n in thesecond cell, n is an integer greater than 0, and K and L arerespectively integers equal to or greater than 1.

The PHICH signal, the PDCCH signal and the PUSCH signal may correspondto the same HARQ process.

The subframes #(n−L), #(n−K) and #n may be allocated to the same HARQprocess.

L may be identical to K when the second cell is configured as UL in theUU and L may be greater than K when the second cell is not configured asUL in the UL subframe UU.

When the second cell is not configured as UL in the UU, a process ofreceiving a PHICH signal and a UL grant PDCCH signal may be omitted in aDL subframe relating to the UU according to a parameter value set to thespecific TDD UL-DL configuration.

The first cell may be a scheduling cell and the second cell may be ascheduled cell.

Advantageous Effects

According to the present invention, a signal can be efficientlytransmitted/received in a wireless communication system. Furthermore, asignal can be efficiently transmitted/received in a multicarrier systemsupporting TDD. In addition, existing signal transmitting/receivingtiming can be reused when signal transmitting/receiving timing isconfigured in a multicarrier system supporting TDD.

The effects of the present invention are not limited to theabove-described effects and other effects which are not described hereinwill become apparent to those skilled in the art from the followingdescription.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a radio frame structure;

FIG. 2 illustrates a resource grid of a downlink slot;

FIG. 3 illustrates a downlink subframe structure;

FIG. 4 illustrates an uplink subframe structure;

FIGS. 5 and 6 illustrate TDD UL ACK/NACK (UplinkAcknowledgement/Negative Acknowledgement) transmission timing in asingle cell case;

FIGS. 7 and 8 illustrate TDD PUSCH (Physical Uplink Shared Channel)transmission timing in a single cell case;

FIGS. 9 and 10 illustrate TDD DL ACK/NACK transmission timing in asingle cell case;

FIG. 11 illustrates a TDD HARQ (Hybrid Automatic Repeat request) processin a single cell situation;

FIG. 12 illustrates a carrier aggregation (CA) communication system;

FIG. 13 illustrates scheduling in case of aggregation of a plurality ofcarriers;

FIGS. 14 to 16 illustrate an ACK/NACK timing setting and transmissionmethod according to embodiment 1;

FIGS. 17 and 18 illustrate a UL grant/PHICH timing setting methodaccording to embodiment 1;

FIG. 19 illustrates CA combinations to which ACK/NACK timing ofembodiments 1 and 2 is applied;

FIG. 20 illustrates CA combinations which cause a problem in configuringUL HARQ timing;

FIGS. 21 to 25 illustrate a method for configuring UG or PHICH timingfor SCC U according to embodiment 3;

FIGS. 26 to 29 illustrate a method for configuring UG or PHICH timingfor SCC U according to embodiment 4; and

FIG. 30 illustrates a base station (BS) and a user equipment (UE)applicable to an embodiment of the present invention.

BEST MODE

Embodiments of the present invention are applicable to a variety ofwireless access technologies such as Code Division Multiple Access(CDMA), Frequency Division Multiple Access (FDMA), Time DivisionMultiple Access (TDMA), Orthogonal Frequency Division Multiple Access(OFDMA), and Single Carrier Frequency Division Multiple Access(SC-FDMA). CDMA can be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA can be implemented as a radiotechnology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwideinteroperability for Microwave Access (WiMAX)), IEEE 802.20, EvolvedUTRA (E-UTRA). UTRA is a part of Universal Mobile TelecommunicationsSystem (UMTS). 3^(rd) Generation Partnership Project (3GPP) Long TermEvolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA,employing OFDMA for downlink and SC-FDMA for uplink. LTE-Advanced(LTE-A) is an evolution of 3GPP LTE.

While the following description is given, centering on 3GPP LTE/LTE-A toclarify the description, this is purely exemplary and thus should not beconstrued as limiting the present invention.

FIG. 1 illustrates a radio frame structure.

Referring to FIG. 1, a radio frame used in 3GPP LTE(-A) has a length of10 ms (307200 Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD (Frequency Division Duplex) mode, and thus the radioframe includes only one of a downlink subframe and an uplink subframe ina specific frequency band.

Particularly, FIG. 1 shows a radio frame structure for TDD, used in 3GPPLTE(-A). Table 1 shows UL-DL configurations of subframes in a radioframe in the TDD mode.

TABLE 1 Downlink- to-Uplink Uplink- Switch- downlink point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  DS U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D DD D 6 5 ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes DwPTS(Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS (Uplink PilotTimeSlot). DwPTS is a period reserved for downlink transmission andUpPTS is a period reserved for uplink transmission. Table 2 showsspecial subframe configuration.

TABLE 2 Normal cyclic prefix in Extended cyclic prefix in downlinkdownlink UpPTS UpPTS Normal Extended Normal Extended Special cycliccyclic cyclic cyclic subframe prefix in prefix prefix in prefix inconfiguration DwPTS uplink in uplink DwPTS uplink uplink 0  6592 · T_(s)2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 119760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

FIG. 2 illustrates a resource grid of a downlink slot.

Referring to FIG. 2, a downlink slot includes a plurality of OFDMsymbols in the time domain. One downlink slot may include 7(6) OFDMsymbols, and one resource block (RB) may include 12 subcarriers in thefrequency domain. Each element on the resource grid is referred to as aresource element (RE). One RB includes 12×7(6) REs. The number N_(RB) ofRBs included in the downlink slot depends on a downlink transmitbandwidth. The structure of an uplink slot may be same as that of thedownlink slot except that OFDM symbols by replaced by SC-FDMA symbols.

FIG. 3 illustrates a downlink subframe structure.

Referring to FIG. 3, a maximum of three (four) OFDM symbols located in afront portion of a first slot within a subframe correspond to a controlregion to which a control channel is allocated. The remaining OFDMsymbols correspond to a data region to which a physical downlink sharedchancel (PDSCH) is allocated. A PDSCH is used to carry a transport block(TB) or a codeword (CW) corresponding to the TB. The TB means a datablock transmitted from a MAC layer to a PHY layer through a transportchannel. The codeword corresponds to a coded version of a TB. Thecorresponding relationship between the TB and the CW depends on swiping.In the specifically, the PDSCH, TB and CW are interchangeably used.Examples of downlink control channels used in LTE(-A) include a physicalcontrol format indicator channel (PCFICH), a physical downlink controlchannel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc.The PCFICH is transmitted at a first OFDM symbol of a subframe andcarries information regarding the number of OFDM symbols used fortransmission of control channels within the subframe. The PHICH is aresponse of uplink transmission and carries an HARQ acknowledgment(ACK)/not-acknowledgment (NACK) signal. A HARQ-ACK response includespositive ACK (simply, ACK), negative ACK (NACK), DTX (DiscontinuousTransmission) or NACK/DTX. Here, HARQ-ACK is used with HARQ ACK/NACK andACK/NACK interchangeably.

Control information transmitted through the PDCCH is referred to asdownlink control information (DCI). The DCI includes resource allocationinformation for a UE or a UE group and other control information. Forexample, the DCI includes uplink/downlink scheduling information, anuplink transmit (Tx) power control command, etc. Transmission modes andinformation content of DCI formats for configuring a multi-antennatechnology are as follows.

Transmission Mode

-   -   Transmission mode 1: Transmission from a single base station        antenna port    -   Transmission mode 2: Transmit diversity    -   Transmission mode 3: Open-loop spatial multiplexing    -   Transmission mode 4: Closed-loop spatial multiplexing    -   Transmission mode 5: Multi-user MIMO    -   Transmission mode 6: Closed-loop rank-1 precoding    -   Transmission mode 7: Transmission using UE-specific reference        signals

DCI Format

-   -   Format 0: Resource grants for the PUSCH transmissions (uplink)    -   Format 1: Resource assignments for single codeword PDSCH        transmissions (transmission modes 1, 2 and 7)    -   Format 1A: Compact signaling of resource assignments for single        codeword PDSCH (all modes)    -   Format 1B: Compact resource assignments for PDSCH using rank−1        closed loop precoding (mod 6)    -   Format 1C: Very compact resource assignments for PDSCH (e.g.        paging/broadcast system information)    -   Format 1D: Compact resource assignments for PDSCH using        multi-user MIMO (mode 5)    -   Format 2: Resource assignments for PDSCH for closed-loop MIMO        operation (mode 4)    -   Format 2A: Resource assignments for PDSCH for open-loop MIMO        operation (mode 3)    -   Format 3/3A: Power control commands for PUCCH and PUSCH with        2-bit/1-bit power adjustments

As described above, the PDCCH may carry a transport format and aresource allocation of a downlink shared channel (DL-SCH), resourceallocation information of an uplink shared channel (UL-SCH), paginginformation on a paging channel (PCH), system information on the DL-SCH,information on resource allocation of an upper-layer control messagesuch as a random access response transmitted on the PDSCH, a set of Txpower control commands on individual UEs within an arbitrary UE group, aTx power control command, information on activation of a voice over IP(VoIP), etc. A plurality of PDCCHs can be transmitted within a controlregion. The UE can monitor the plurality of PDCCHs. The PDCCH istransmitted on an aggregation of one or several consecutive controlchannel elements (CCEs). The CCE is a logical allocation unit used toprovide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). A format of the PDCCH and the number of bits of the availablePDCCH are determined by the number of CCEs. The BS determines a PDCCHformat according to DCI to be transmitted to the UE, and attaches acyclic redundancy check (CRC) to control information. The CRC is maskedwith a unique identifier (referred to as a radio network temporaryidentifier (RNTI)) according to an owner or usage of the PDCCH. If thePDCCH is for a specific UE, a unique identifier (e.g., cell-RNTI(C-RNTI)) of the UE may be masked to the CRC. Alternatively, if thePDCCH is for a paging message, a paging identifier (e.g., paging-RNTI(P-RNTI)) may be masked to the CRC. If the PDCCH is for systeminformation (more specifically, a system information block (SIB)), asystem information RNTI (SI-RNTI) may be masked to the CRC. When thePDCCH is for a random access response, a random access-RNTI (RA-RNTI)may be masked to the CRC.

FIG. 4 illustrates an uplink subframe structure.

Referring to FIG. 4, an uplink subframe includes a plurality of (e.g. 2)slots. A slot may include different numbers of SC-FDMA symbols accordingto CP lengths. The uplink subframe is divided into a control region anda data region in the frequency domain. The data region is allocated witha PUSCH and used to carry a data signal such as audio data. The controlregion is allocated a PUCCH and used to carry uplink control information(UCI). The PUCCH includes an RB pair located at both ends of the dataregion in the frequency domain and hopped in a slot boundary.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response to a downlink data packet        (e.g. codeword) on a PDSCH and indicates whether the downlink        data packet has been successfully received. A 1-bit ACK/NACK        signal is transmitted as a response to a single downlink        codeword and a 2-bit ACK/NACK signal is transmitted as a        response to two downlink codewords. A HARQ response includes        positive ACK (simply, ACK), negative ACK (NACK), DTX        (Discontinuous Transmission) or NACK/DTX. Here, HARQ-ACK is used        with HARQ ACK/NACK and ACK/NACK interchangeably.    -   Channel State Information (CSI): This is feedback information        about a downlink channel. MIMO (Multiple Input Multiple        Output)-related feedback information includes a rank indicator        (RI) and a precoding matrix indicator (PMI). 20 bits per        subframe are used.

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a SoundingReference Signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon.

Table 3 shows the mapping relationship between PUCCH formats and UCI inLTE-(-A).

TABLE 3 PUCCH format UCI (Uplink Control Information) Format 1 SR(Scheduling Request) (non-modulated waveform) Format 1a 1-bit HARQACK/NACK (SR exist/non-exist) Format 1b 2-bit HARQ ACK/NACK (SRexist/non-exist) Format 2 CQI (20 coded bits) Format 2 CQI and 1- or2-bit HARQ ACK/NACK (20 bits) (corresponding to only extended CP) Format2a CQI and 1-bit HARQ ACK/NACK (20 + 1 coded bits) Format 2b CQI and2-bit HARQ ACK/NACK (20 + 2 coded bits) Format 3 Up to 24-bit HARQACK/NACK + SR (LTE-A)

A description will be given of TDD signal transmission timing in asingle carrier (or cell) situation with reference to FIGS. 5 to 10.

FIGS. 5 and 6 illustrate PDSCH-UL ACK/NACK timing. Here, UL ACK/NACKmeans ACK/NACK transmitted on uplink, as a response to DL data (e.g.PDSCH).

Referring to FIG. 5, a UE can receive one or more PDSCH signals in M DLsubframes (SFs) (S502_0 to S502_M−1). Each PDSCH signal is used totransmit one or more (e.g. 2) transport blocks (TBs) according totransmission mode. A PDCCH signal indicating SPS (Semi-PersistentScheduling) may also be received in step S502_0 to S502_M−1, which isnot shown. When a PDSCH signal and/or an SPS release PDCCH signal ispresent in the M DL subframes, the UE transmits ACK/NACK through a ULsubframe corresponding to the M DL subframes via processes fortransmitting ACK/NACK (e.g. ACK/NACK (payload) generation, ACK/NACKresource allocation, etc.) (S504). ACK/NACK includes acknowledgementinformation about the PDSCH signal and/or an SPS release PDCCH receivedin step S502_0 to S502_M−1. While ACK/NACK is transmitted through aPUCCH basically, ACK/NACK is transmitted through a PUSCH when a PUSCH istransmitted at ACK/NACK transmission time. Various PUCCH formats shownin Table 3 can be used for ACK/NACK transmission. To reduce the numberof ACK/NACK bits transmitted through a PUCCH format, various methodssuch as ACK/NACK bundling and ACK/NACK channel selection can be used.

As described above, in TDD, ACK/NACK relating to data received in the MDL subframes is transmitted through one UL subframe (i.e. M DL SF(s): 1UL SF) and the relationship therebetween is determined by a DASI(Downlink Association Set Index).

Table 4 shows DASI (K: {k0, k1, . . . , k−1}) defined in LTE(-A). Table4 shows spacing between a UL subframe transmitting ACK/NACK and a DLsubframe relating to the UL subframe. Specifically, when a PDCCH thatindicates PDSCH transmission and/or SPS release is present in a subframen−k (kεK), the UE transmits ACK/NACK in a subframe n.

TABLE 4 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 —4 — — 6 — 8 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 75 — — 7 7 —

FIG. 6 illustrates UL ACK/NACK transmission timing when UL-DLconfiguration #1 is configured. In the figure, SF#0 to #9 and SF#10 to#19 respectively correspond to radio frames, and numerals in blocksdenote UL subframes relating to DL subframes. For example, ACK/NACK fora PDSCH of SF#5 is transmitted in SF#5+7 (=SF#12) and ACK/NACK for aPDSCH of SF#6 is transmitted in SF#6+6 (=SF#12). Accordingly, bothACKs/NACKs for DL signals of SF#5/#6 are transmitted in SF#12.Similarly, ACK/NACK for a PDSCH of SF#14 is transmitted in SF#14+4(=SF#18).

FIGS. 7 and 8 illustrate PHICH grant-PUSCH timing. A PUSCH can betransmitted corresponding to a PDCCH (UL grant) and/or a PHICH (NACK).

Referring to FIG. 7, the UE can receive a PDCCH (UL grant) and/or aPHICH (NACK) through a PDCCH (S702). Here, NACK corresponds to anACK/NACK response to previous PUSCH transmission. In this case, the UEcan initially transmit/retransmit one or more TBs through a PUSCH afterk subframes via processes for PUSCH transmission (e.g. TB coding, TB-CWswiping, PUSCH resource allocation, etc.) (S704). The present embodimentis based on the assumption that a normal HARQ operation in which a PUSCHis transmitted once is performed. In this case, a PHICH and a UL grantcorresponding to PUSCH transmission are present in the same subframe.However, in case of subframe bundling in which a PUSCH is transmittedmultiple times through a plurality of subframes, a PHICH and a UL grantcorresponding to PUSCH transmission may be present in differentsubframes.

Table 5 shows a UAI (Unlink Association Index) (k) for PUSCHtransmission in LTE(-A). Table 5 shows spacing between a DL subframefrom which a PHICH/UL grant is detected and a UL subframe relating tothe DL subframe. Specifically, when a PHICH/UL grant is detected from asubframe n, the UE can transmit a PUSCH in a subframe n+k.

TABLE 5 TDD UL-DL subframe number n Configuration 0 1 2 3 4 5 6 7 8 9 04 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

FIG. 8 illustrates PUSCH transmission timing when UL-DL configuration #1is configured. In the figure, SF#0 to #9 and SF#10 to #19 respectivelycorrespond to radio frames, and numerals in blocks denote UL subframesrelating to DL subframes. For example, a PUSCH corresponding to PHICH/ULgrant of SF#6 is transmitted in SF#6+6 (=SF#12) and a PUSCHcorresponding to a PHICH/UL grant of SF#14 is transmitted in SF#14+4(=SF#18).

FIGS. 9 and 10 illustrate PUSCH-PHICH/UL grant timing. A PHICH is usedto transmit DL ACK/NACK. Here, DL ACK/NACK means ACK/NACK transmitted ondownlink as a response to UL data (e.g. PUSCH).

Referring to FIG. 9, the UE transmits a PUSCH signal to the BS (S902).Here, the PUSCH signal is used to transmit one or a plurality of (e.g.2) TBs according to transmission mode. The BS can transmit ACK/NACK as aresponse to PUSCH transmission through a PHICH after k subframes viaprocesses for ACK/NACK transmission (e.g. ACK/NACK generation, ACK/NACKresource allocation, etc.) (S904). ACK/NACK includes acknowledgementinformation about the PUSCH signal of step S902. When a response toPUSCH transmission is NACK, the BS can transmit a UL grant PDCCH forPUSCH retransmission to the UE after k subframe (S904). The presentembodiment is based on the assumption that a normal HARQ operation inwhich a PUSCH is transmitted once is performed. In this case, a PHICHand UL grant used for PUSCH transmission can be transmitted in the samesubframe. In case of subframe bundling, however, the PHICH and UL grantused for PUSCH transmission can be transmitted in different subframes.

Table 6 shows a UAI for PHICH/UL grant transmission in LTE(-A). Table 6shows spacing between a DL subframe in which a PHICH/UL grant is presentand a UL subframe relating to the DL subframe. Specifically, a PHICH/ULgrant of a subframe i corresponds to PUSCH transmission through asubframe i−k.

TABLE 6 TDD UL-DL subframe number i Configuration 0 1 2 3 4 5 6 7 8 9 07 4 7 4 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 6 4 7 4 6

FIG. 10 illustrates PHICH/UL grant transmission timing when UL-DLconfiguration #1 is configured. In the figure, SF#0 to #9 and SF#10 to#19 respectively correspond to radio frames, and numerals in blocksdenote DL subframes relating to UL subframes. For example, a PHICH/ULgrant corresponding to a PUSCH of SF#2 is transmitted in SF#2+4 (=SF#6)and a PHICH/UL grant corresponding to a PUSCH of SF#8 is transmitted inSF#8+6 (=SF#14).

PHICH resource allocation will now be described. When a PUSCH istransmitted in subframe #n, the UE determines a PHICH resourcecorresponding to the PUSCH in subframe #(n+k_(PHICH)). In case of FDD,k_(PHICH) has a fixed value (e.g. 4). In case of TDD, k_(PHICH) has avalue depending on UL-DL configuration. Table 7 shows k_(PHICH) for TDDis equivalent to Table 6.

TABLE 7 TDD UL-DL UL subframe index n Configuration 0 1 2 3 4 5 6 7 8 90 4 7 6 4 7 6 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 4 6 6 4 7

A PHICH resource is provided by [PHICH group index, orthogonal sequenceindex]. The PHICH group index and the orthogonal sequence index aredetermined using (i) a lowest PRB index used for PUSCH transmission and(ii) a 3-bit field value for DMRS (Demodulation Reference Signal) cyclicshift. Here, (i) and (ii) are indicated by a UL grant PDCCH.

A description will be given of a HARQ process. The UE executes aplurality of parallel HARQ processes for UL transmission. The pluralityof parallel HARQ processes is used to continuously perform ULtransmission while the UE waits for HARQ feedback representing whetherprevious UL transmission has been successful or not. Each HARQ processrelates to a HARQ buffer of a MAC (Medium Access Control) layer. EachHARQ process manages the number of transmissions of a MAC PDU (PhysicalData Unit) in the buffer, HARQ feedback for the MAC PDU in the buffer,and a state parameter regarding a current redundancy version.

In case of LTE(-A) FDD, the number of UL HARQ processes for non-subframebundling operation (i.e. normal HARQ operation) is 8. In case of LTE(-A)TDD, the number of UL HARQ processes and HARQ RTT (Round Trip Time) areconfigured differently according to DL-UL configurations because thenumber of UL subframes depends on UL-DL configuration. Here, the HARQRTT may be a time interval (in the unit of SF or ms, for example)between a time when a UL grant is received and a time when a PHICH(corresponding to the UL grant) is received through transmission of aPUSCH (corresponding the UL grant) or a time interval between a PUSCHtransmission time and a PUSCH retransmission time.

The number of UL HARQ processes varies. When subframe bundling isapplied, a bundle of PUSCHs configured of 4 contiguous UL subframes istransmitted in FDD and TDD. Accordingly, a HARQ operation/process whensubframe bundling is applied is different from the normal HARQoperation/process.

Table 8 shows the number of synchronous UL HARQ processes and HARQ RTTin TDD. When the UL HARQ RTT is 10 [SFs or ms] (UL-DL configurations #1,#2, #3, #4 and #5), one UL HARQ process uses one fixed UL SF timing.When the UL HARQ RTT does not correspond to 10 [SFs or ms] (UL-DLconfigurations #0 and #6), one UL HARQ process uses a plurality of UL SFtimings (instead of one fixed UL SF timing) while hopping. For example,in case of UL-DL configuration #6, PUSCH transmission timings in one ULHARQ process are: SF #2: PUSCH=>SF #13: PUSCH (RTT: 11 SFs)=>SF #24:PUSCH (RTT: 11 SFs)=>SF #37: PUSCH (RTT: 13 SFs)=>SF #48: PUSCH (RTT: 11SFs)=>SF #52: PUSCH (RTT: 14 SFs).

TABLE 8 Number of HARQ UL-DL Number of processes for configuration ULSFs normal HARQ operation HARQ RTT 0 6 7 11 or 13 1 4 4 10 2 2 2 10 3 33 10 4 2 2 10 5 1 1 10 6 5 6 11 or 13 or 14

In case of TDD UL-DL configurations #1 to #6 and normal HARQ operation,the UE transmits a corresponding PUSCH signal in subframe n+k (refer toTable 5) according to UL grant PDCCH and/or PHICH information upondetection of the UL grant PDCCH and/or PHICH information in subframe n.

In case of TDD UL-DL configuration #0 and the normal HARQ operation,when a UL DCI grant PDCCH and/or a PHICH are detected from subframe n,PUSCH transmission timing of the UE is varied according to conditions.When the MSB (Most Significant bit) of a UL index in DCI is 1 or thePHICH is received through a resource corresponding to I_(PHICH)=0 insubframe #0 or #5, the UE transmits the corresponding PUSCH signal insubframe n+k (refer to Table 5). When the LSB (Least Significant bit) ofthe UL index in the DCI is 1, the PHICH is received through a resourcecorresponding to I_(PHICH)=1 in subframe #0 or #5, or the PHICH isreceived in subframe #1 or #6, UE transmits the corresponding PUSCHsignal in subframe n+7. When both the MSB and LSB in the DCI are set,the UE transmits the corresponding PUSCH signal in subframe n+k (referto Table 5) and subframe n+7.

FIG. 11 illustrates a synchronous UL HARQ process when UL-DLconfiguration #1 is configured. Numerals in blocks denote UL HARQprocess numbers. The synchronous UL HARQ process shown in FIG. 11corresponds to a normal HARQ process. Referring to FIG. 11, HARQ process#1 involves SF#2, SF#6, SF#12 and SF#16. For example, if an initialPUSCH signal (e.g. RV=0) is transmitted in SF#2, a UL grant PDCCH and/ora PHICH corresponding to the PUSCH signal can be received in SF#6 and a(retransmission) PUSCH signal (e.g. RV=2) corresponding to the initialPUSCH signal can be transmitted in SF#12. Accordingly, 4 UL HARQprocesses having an RTT (Round Trip Time) of 10 SFs (or 10 ms) arepresent in case of UL-DL configuration #1.

FIG. 12 illustrates a carrier aggregation (CA) communication system. Touse a wider frequency band, an LTE-A system employs CA (or bandwidthaggregation) technology which aggregates a plurality of UL/DL frequencyblocks to obtain a wider UL/DL bandwidth. Each frequency block istransmitted using a component carrier (CC). The CC can be regarded as acarrier frequency (or center carrier, center frequency) for thefrequency block.

Referring to FIG. 12, a plurality of UL/DL CCs can be aggregated tosupport a wider UL/DL bandwidth. The CCs may be contiguous ornon-contiguous in the frequency domain. Bandwidths of the CCs can beindependently determined. Asymmetrical CA in which the number of UL CCsis different from the number of DL CCs can be implemented. For example,when there are two DL CCs and one UL CC, the DL CCs can correspond tothe UL CC in the ratio of 2:1. A DL CC/UL CC link can be fixed orsemi-statically configured in the system. Even if the system bandwidthis configured with N CCs, a frequency band that a specific UE canmonitor/receive can be limited to M (<N) CCs. Various parameters withrespect to CA can be configured cell-specifically,UE-group-specifically, or UE-specifically. Control information may betransmitted/received only through a specific CC. This specific CC can bereferred to as a Primary CC (PCC) (or anchor CC) and other CCs can bereferred to as Secondary CCs (SCCs).

In LTE-A, the concept of a cell is used to manage radio resources. Acell is defined as a combination of downlink resources and uplinkresources. Yet, the uplink resources are not mandatory. Therefore, acell may be composed of downlink resources only or both downlinkresources and uplink resources. The linkage between the carrierfrequencies (or DL CCs) of downlink resources and the carrierfrequencies (or UL CCs) of uplink resources may be indicated by systeminformation. A cell operating in primary frequency resources (or a PCC)may be referred to as a primary cell (PCell) and a cell operating insecondary frequency resources (or an SCC) may be referred to as asecondary cell (SCell). The PCell is used for a UE to establish aninitial connection or re-establish a connection. The PCell may refer toa cell operating on a DL CC SIB2-linked to a UL CC. Furthermore, thePCell may refer to a cell indicated during handover. The SCell may beconfigured after an RRC connection is established and may be used toprovide additional radio resources. The PCell and the SCell maycollectively be referred to as a serving cell. Accordingly, a singleserving cell composed of a PCell only exists for a UE in anRRC_Connected state, for which CA is not configured or which does notsupport CA. On the other hand, one or more serving cells exist,including a PCell and entire SCells, for a UE in an RRC_CONNECTED state,for which CA is configured. For CA, a network may configure one or moreSCells in addition to an initially configured PCell, for a UE supportingCA during connection setup after an initial security activationoperation is initiated.

FIG. 13 illustrates scheduling when a plurality of carriers isaggregated. It is assumed that 3 DL CCs are aggregated and DL CC A isconfigured as a PDCCH CC. DL CC A, DL CC B and DL CC C can be calledserving CCs, serving carriers, serving cells, etc. In case of CIF(Carrier Indicator Field) disabled, a DL CC can transmit only a PDCCHthat schedules a PDSCH corresponding to the DL CC without a CIF(non-cross-CC scheduling). When the CIF is enabled according toUE-specific (or UE-group-specific or cell-specific) higher layersignaling, a specific CC (e.g. DL CC A) can transmit not only a PDCCHthat schedules the PDSCH corresponding to the DL CC A but also PDCCHsthat schedule PDSCHs of other DL CCs using the CIF (cross-CCscheduling). A PDCCH is not transmitted in DL CC B/C.

A specific CC (or cell) used for PDCCH transmission is called ascheduling CC (or scheduling cell). The scheduling CC (or cell) may beused with a monitoring CC (or MCC) interchangeably. A CC (or cell) inwhich a PDSCH/PUSCH is scheduled by a PDCCH of another CC is called ascheduled CC (or scheduled cell). One or more scheduling CCs may beconfigured for one UE and one of the scheduling CCs may be used for DLcontrol signaling and UL PUCCH transmission. That is, a scheduling CCincludes a PCC. When only one scheduling CC is configured, thescheduling CC corresponds to the PCC. The scheduling CC/scheduled CC mayalso be called MCC/SCC in the following description.

When cross-CC scheduling is configured, CCs carrying signals are definedaccording to signal type as follows.

-   -   PDCCH (UL/DL grant): scheduling CC (or MCC)    -   PDSCH/PUSCH: CC indicated by a CIF of a PDCCH, detected from a        scheduling CC    -   DL ACK/NACK (e.g. PHICH): scheduling CC (or MCC) (e.g. DL PCC)    -   UL ACK/NACK (e.g. PUCCH): UL PCC

A conventional CA TDD system considers only a case in which aggregatedCCs have the same UL-DL configuration. In this case, TDD signaltransmission timing in a single cell situation, described with referenceto FIGS. 5 to 10, can be used because all CCs have the same DL/ULsubframe timing. However, a scheme for independently configuring UL-DLconfigurations for respective CCs in consideration of a UL/DL loaddifference and a channel state difference between CCs is underdiscussion recently. If a plurality of CCs has different UL-DLconfigurations when cross-CC scheduling is applied, however, thefollowing problem may be generated in relation to signaltransmission/reception timing. Furthermore, it may be necessary todefine a new UL/DL ACK/NACK timing and/or UL/DL grant timing.

To solve the above-described problem, the present invention proposes asignal transmission timing (e.g. UL ACK/NACK transmission timing, ULgrant transmission timing and DL ACK/NACK transmission timing) settingscheme in a system supporting CA and TDD. In addition, the presentinvention proposes a method of configuring a UL HARQ process accordingto signal transmission timing. In the following description, UL ACK/NACKis simply called ACK/NACK, a UL grant is called UG, and DL ACK/NACK iscalled a PHICH for convenience.

Here, ACK/NACK timing may mean a U configured to transmit ACK/NACK forDL data (e.g. a PDSCH) received through a specific D or mean a timeinterval between the D in which the DL data is received and the U inwhich ACK/NACK is transmitted. UG timing may mean a D configured toreceive a UG that schedules UL data (e.g. a PUSCH) transmitted through aspecific U or mean a time interval between the D in which the UG isreceived and the U in which the UL data is transmitted. PHICH timing maymean a D configured to receive ACK/NACK for UL data (e.g. a PUSCH)transmitted through a specific U or mean a time interval between the Uin which the UL data is transmitted and the D in which ACK/NACK isreceived. ACK/NACK timing configured for a specific CC or specificUD-cfg corresponds to timing of Table 4, for example. UG timingconfigured for a specific CC or specific UD-cfg corresponds to timing ofTable 5, for example. PHICH timing configured for a specific CC orspecific UD-cfg corresponds to timings of Tables 6 and 7, for example.

In case of ACK/NACK, the proposed method described below can be appliedirrespective of non-cross-CC scheduling and cross-CC scheduling. In caseof UG or PHICH, the proposed method described below can be applied onlywhen a cross-CC scheduling mode is configured or cross-CC scheduling isperformed. For example, if a scheduling CC schedules only itself eventhough a cross-CC scheduling mode has been configured (i.e. non-cross-CCscheduling), the following method may not be used. In this case, TDDsignal transmission timing configured for the scheduling CC can beapplied.

In the following description, for easy understanding of the presentinvention, it is assumed that a PCC and an SCC having different UL-DLconfigurations are aggregated regarding ACK/NACK timing configuration.Furthermore, it is assumed that an MCC and an SCC having different UL-DLconfigurations are aggregated regarding UG or PHICH timingconfiguration. However, the proposed method described below isapplicable to each of a plurality of SCCs having different UL-DLconfigurations. For example, when a PCC (in case of ACK/NACK timing) oran MCC (incase of UG or PHICH timing) and a plurality of SCCs havingdifferent UL-DL configurations are present, the proposed methoddescribed below can be independently applied to each SCC and the PCC oreach SCC or the MCC.

In the following description, D denotes a DL SF, S denotes a special SF,and U denotes a UL SF. It is assumed that D or U is used as S and,unless otherwise specified, D is used as S. In addition, the unit of SFor ms may be called a TTI (Transmission Time Interval. A CC is usedinterchangeably with a cell (or serving cell) and a PCC and an SCC maybe respectively used interchangeably with a PCell and an SCell.

In the following description, a signal transmission/reception process isperformed by a UE. If a BS (or relay) performs the signaltransmission/reception process, only a signal transmission/receptiondirection is changed and the same process as the signaltransmission/reception process performed by the UE can be carried out bythe BS.

Embodiment 1 Configuring Signal Transmission/Reception Timing

ACK/NACK Timing—Method 1-1

When a PCC and an SCC having different UL-DL configurations areaggregated, the following ACK/NACK timing setting rule can beconsidered. Method 1-1 may include a cross-SF scheduling operationduring cross-CC scheduling. Here, cross-SF scheduling means schedulingof a DL data to be transmitted through DL SF #(n+k) (k>0) in DL SF #n.

-   -   ACK/NACK for DL data received through PCC        -   ACK/NACK timing of PCC can be applied.        -   Misalignment between a BS and a UE can be prevented at least            for the ACK/NACK timing of the PCC during reconfiguration            into a single CC from multi-CC (or reconfiguration into            multi-CC from a single CC).    -   ACK/NACK for DL data received through SCC        -   First, UL-DL configuration(s), in which SF(s) corresponding            to SF(s) where both the PCC and SCC are U is all configured            as U, can be selected from among all UL-DL configurations            (e.g. Table 1). Then, a UL-DL configuration having a            smallest number of Us (equivalently, a largest number of Ds)            is selected from the selected UL-DL configuration(s), and            ACK/NACK timing configured thereto can be applied.            Equivalently, UL-DL configuration(s), in which SF(s)            corresponding to SF(s) where either the PCC or the SCC is D            is all configured as D, can be selected from all the UL-DL            configurations. Then, a UL-DL configuration (referred to as            “DL union” hereinafter) having a smallest number of Ds            (equivalently, a largest number of Us) is selected from            among the selected UL-DL configuration(s), and ACK/NACK            timing (referred to as “common ACK/NACK timing” hereinafter)            configured for the DL union can be applied.        -   In case of the DL union, D/U is configured such that            ACK/NACK timing for D of the SCC can be configured to U of            the PCC.        -   Preferably, only ACK/NACK timing of D having the same SF            timing as D of the SCC can be extracted from the DL union            and applied.    -   The common ACK/NACK timing can be applied to all DL data        received through the PCC and the SCC.

FIGS. 14 and 15 illustrate an ACK/NACK timing setting scheme accordingto the present embodiment. It is assumed that the PCC and the MCC areidentical and thus the MCC is also denoted as a PCC. In addition, UL-DLconfiguration is represented as UD-cfg.

FIG. 14 illustrates a case in which the PCC and the SCC respectivelycorrespond to UD-cfg #3 and UD-cfg#6. In this case, method 1-1 isapplied as follows.

-   -   ACK/NACK for DL data received through the PCC        -   ACK/NACK timing of the PCC (i.e. UD-cfg #3) can be applied.    -   ACK/NACK for DL data received through the SCC        -   ACK/NACK timing configured for UD-cfg (i.e. UD-cfg#3)(*)            having a smallest number of Us among UD-cfgs (i.e. UD-cfgs            #0, #3 and #6), in which SFs (i.e. SFs #2, #3 and #4) where            both the PCC and the SCC are U are all configured as U, can            be applied (refer to FIG. 14(a)). Equivalently, ACK/NACK            timing configured for UD-cfg (i.e. UD-cfg#3)(*) having a            smallest number of Ds among UD-cfgs (i.e. UD-cfgs #3, #4 and            #5), in which SFs (i.e. SFs #0, #1, #5, #6, #7, #8 and #9)            where either the PCC or the SCC is D is all configured as D,            can be applied (refer to FIG. 14(b)).

FIG. 15 illustrates a case in which the PCC and the SCC respectivelycorrespond to UD-cfg #2 and UD-cfg#4. In this case, method 1-1 isapplied as follows.

-   -   ACK/NACK for DL data received through the PCC        -   ACK/NACK timing of the PCC (i.e. UD-cfg #2) can be applied.    -   ACK/NACK for DL data received through the SCC        -   ACK/NACK timing configured for UD-cfg (i.e. UD-cfg#5)(*)            having a smallest number of Us among UD-cfgs (i.e. UD-cfgs            #0 to #6), in which SF(s) (i.e. SF #2) where both the PCC            and the SCC are U is all configured as U, can be applied            (refer to FIG. 15(a)). Equivalently, ACK/NACK timing            configured for UD-cfg (i.e. UD-cfg#5)(*) having a smallest            number of Ds among UD-cfg (i.e. UD-cfg #5), in which SFs            (i.e. SFs #0, #1 and #3 to #9) where either the PCC or the            SCC is D are all configured as D, can be applied (refer to            FIG. 15(b)).

ACK/NACK Timing—Method 1-2

When a plurality of CCs (e.g. a PCC, an MCC and an SCC; PCC(=MCC) and anSCC) having different TDD UL-DL configurations are aggregated, thefollowing ACK/NACK timing setting rule can be considered in order not tointroduce an additional cross-SF scheduling operation during cross-CCscheduling.

[Alt 0]

-   -   ACK/NACK for DL data received through the PCC        -   ACK/NACK timing of the PCC can be applied.    -   ACK/NACK for DL data received through the SCC        -   Non-cross-CC scheduling: ACK/NACK timing configured for DL            union (Method 1-1) of the PCC and SCC can be applied.    -   Cross-CC scheduling: A virtual UL-DL configuration, in which SFs        where an SCC or an MCC configured to cross-CC-schedule the SCC        is U are all configured as U, and the other SFs (i.e. SFs for        which both the corresponding 2 CCs are configured as D) are all        configured as D, is defined as “ULU-cfg”. Finally, ACK/NACK        timing configured for a DL union of the PCC and ULU-cfg can be        applied.    -   Scheduling for D of the SCC can be skipped in an SF        (hereinafter, a collided SF), in which the MCC configured to        cross-CC-schedule the SCC is U and the SCC is D. In this case,        the UE can omit a procedure (e.g. search space monitoring and        blind decoding of PDCCH candidates) for receiving a DL grant DCI        format regarding the SCC in the collided SF.

[Alt 1]

-   -   ACK/NACK for DL data received through the PCC        -   ACK/NACK timing of the PCC can be applied.    -   ACK/NACK for DL data received through the SCC        -   Non-cross-CC scheduling: ACK/NACK timing configured for a DL            union of the PCC and the SCC can be applied.        -   Cross-CC scheduling: ACK/NACK timing configured for a DL            union of the MCC configured to cross-CC-schedule the SCC and            the PCC can be applied.    -   Scheduling for D of the SCC can be skipped in a collided SF, in        which the MCC configured to cross-CC-schedule the SCC is U and        the SCC is D. In this case, the UE can omit a procedure (e.g.        search space monitoring and blind decoding of PDCCH candidates)        for receiving a DL grant DCI format regarding the SCC in the        collided SF.

[Alt 2]

-   -   ACK/NACK for DL data received through the PCC        -   ACK/NACK timing of the PCC can be applied.    -   ACK/NACK for DL data received through the SCC        -   Non-cross-CC scheduling: ACK/NACK timing configured for a DL            union of the PCC and the SCC can be applied.        -   Cross-CC scheduling: ACK/NACK timing of the PCC can be            applied.    -   Scheduling for D of the SCC can be skipped in a collided SF, in        which an MCC configured to cross-CC-schedule the PCC or the SCC        is U and the SCC is D. In this case, the UE can omit a procedure        (e.g. search space monitoring and blind decoding of PDCCH        candidates) for receiving a DL grant DCI format regarding the        SCC in the collided SF.

When ACK/NACK timing is configured using Methods 1-1 and 1-2 (or othermethods), ACK/NACK bit/number to be transmitted may be configureddifferently according to Us of the PCC. In this case, it is possible toconsider configuring/applying different PUCCH resources/formats (e.g.PUCCH format 1a/1b and PUCCH format 3) and/or different transmissionschemes (e.g. multi-bit ACK/NACK coding and ACK/NACK selection) forACK/NACK transmitted through each of Us of the PCC in order toefficiently use ACK/NACK transmission resources.

For example, ACKs/NACKs for the PCC and the SCC can be simultaneouslytransmitted through a specific U (e.g. PCC-U1) of the PCC, whereas onlyACK/NACK for the PCC can be transmitted through another specific U (e.g.PCC-U2) of the PCC. Here, different PUCCH resources and/or differenttransmission schemes (e.g. PUCCH formats) may be applied to ACKs/NACKstransmitted through PCC-U1 and PCC-U2. Specifically, multi-bit ACK/NACKcoding scheme using an explicit PUCCH resource (e.g. PUCCH format 3) canbe applied to ACK/NACK transmitted through PCC-U1, and an ACK/NACKselection scheme using an implicit PUCCH resource (e.g. PUCCH format1a/1b) can be applied to ACK/NACK transmitted through PCC-U2. That is,PUCCH formats and resource allocation schemes can be respectivelydetermined for a case in which ACKs/NACKs for N (e.g. N=2) or more CCsare transmitted through a specific U of the PCC, and for a case in whichACK/NACK for less than N CCs is transmitted through a specific U of thePCC.

FIG. 16 illustrates a procedure of transmitting ACK/NACK according tothe above proposed method. Referring to FIG. 16, the UE generatesACK/NACK information upon reception of DL data (e.g. a PDSCH) (S1602).Then, the UE performs PUCCH resource allocation to transmit the ACK/NACKinformation in subframe #n (S1604). Here, PUCCH resource allocation isdetermined in consideration of that ACK/NACK information for how many(N) CCs is to be transmitted in subframe #n. For example, when N is 1,the ACK/NACK information can be transmitted through PUCCH format 1a/1b(implicit resource) (S1606). When N is 2 or more, the ACK/NACKinformation can be transmitted through PUCCH format 3 (explicitresource) (S1606).

UL Grant (UG) or PHICH Timing—Method 1-3

When an MCC and an SCC having different UL-DL configurations areaggregated, the following UG or PHICH timing setting rule can beconsidered.

-   -   UG or PHICH for UL data transmitted through the MCC        -   UG or PHICH timing of the MCC can be applied.        -   Misalignment between the BS and the UE can be prevented at            least for the UG or PHICH timing of the MCC during            reconfiguration into the non-cross CC scheduling mode from            the cross-CC scheduling mode (or reconfiguration into the            cross-CC scheduling mode from the non-cross-CC scheduling            mode).    -   UG or PHICH for UL data transmitted through the SCC        -   First, UL-DL configuration(s), in which SF(s) where either            the MCC or the SCC is U is all configured as U, can be            selected from all UL-DL configurations. Then, a UL-DL            configuration (referred to as “UL union”) having a smallest            number of Us (equivalently, a largest number of Ds) is            selected from the selected UL-DL-configuration(s), and UG or            PHICH timing (“common UG or PHICH timing) configured for the            UL union can be applied.        -   In case of the UL union, D/U is configured such that UG or            PHICH timing for all Us of the SCC can be configured to D of            the MCC.        -   Preferably, only UG or PHICH timing of U having the same SF            timing as U of the SCC can be extracted from the UL union            and applied.    -   The common ACK/NACK timing can be applied to all UL data        transmitted through the MCC and the SCC.

When UG or PHICH timing is configured using Method 1-3 (or othermethods), a specific D (e.g. MCC-D1) of the MCC, which is not configuredto transmit a UG or PHICH when the MCC operates alone, can be configuredas UG or PHICH timing for PUSCH transmission in a specific U of theMCC/SCC. For convenience, a U of the MCC/SCC corresponding to MCC-D1configured as UG or PHICH timing is called an orphan U. Here, MCC-D1 canbe identified with reference to Tables 1, 6 and 7. In this case, theorphan U (or all Us of a CC including the orphan U) can be used forone-time PUSCH scheduling/transmission depending only on instantaneousUG (without involving a PHICH based HARQ process). Here, one-time PUSCHtransmission means, although a HARQ process is accompanied without aPHICH, to perform only UL grant based (adaptive) retransmission withoutnon-adaptive retransmission. For example, one-time PUSCH transmissioncan be used to carry UL data and/or UCI (e.g. ACK/NACK and/orCQI/PMI/RI, etc.) (which do not involve a PHICH based HARQ process).Otherwise, a scheme of limiting PUSCH scheduling/transmission for theorphan U (or all Us of the CC including the orphan U) and using theorphan U for other purposes (e.g. PUCCH and/or SRS and/or PRACHtransmission) can be considered. In this case, the UE can omit aprocedure (e.g. search space monitoring and blind decoding of PDCCHcandidates) for receiving a UL grant DCI format in the D (i.e. MCC-D1)of the MCC, which corresponds to the orphan U.

FIGS. 17 and 18 illustrate a UG/PHICH timing setting scheme according tothe present embodiment. It is assumed that a PCC and an MCC areidentical and thus the MCC is also denoted as a PCC. In addition, UL-DLconfiguration is represented as UD-cfg.

FIG. 17 illustrates a case in which the PCC and the SCC respectivelycorrespond to UD-cfg #3 and UD-cfg#6. In this case, the proposed methoddescribed above is applied as follows.

-   -   UG or PHICH for UL data transmitted through the PCC        -   UG or PHICH timing of the PCC (i.e. UD-cfg #3) can be            applied.    -   UG or PHICH for UL data transmitted through the SCC        -   UG or PHICH timing configured for UD-cfg (i.e. UD-cfg#6)(*)            having a smallest number of Us among UD-cfgs (i.e. UD-cfgs            #0 and #6), in which SFs (i.e. SFs #2, #3, #4, #7 and #8)            where either the PCC or the SCC is U are all configured as            U, can be applied.

FIG. 18 illustrates a case in which the PCC and the SCC respectivelycorrespond to UD-cfg #2 and UD-cfg#4. In this case, the proposed methoddescribed above is applied as follows.

-   -   UG or PHICH for UL data transmitted through the PCC        -   UG or PHICH timing of the PCC (i.e. UD-cfg #2) can be            applied.    -   UG or PHICH for UL data transmitted through the SCC        -   UG or PHICH timing configured for UD-cfg (i.e. UD-cfg#1)(*)            having a smallest number of Us among UD-cfgs (i.e. UD-cfgs            #0, #1 and #6), in which SF(s) (i.e. SFs #2, #3 and #7)            where either the PCC or the SCC is U are all configured as            U, can be applied.

Embodiment 2 Configuring Signal Transmission/Reception Timing

When the method of embodiment 1 is applied, ACK/NACK timing, UG timingand PHICH timing can be determined according to a UD-cfg that is not setto any of aggregated CCs (e.g. PCC and SCC). However, in view of D or U,one of UD-cfg of the PCC and UD-cfg of the SCC is included in the other(that is, a nested structure is employed), ACK/NACK timing, UG timingand PHICH timing follow timing set to either UD-cfg of the PCC or SCCwhen the method of embodiment 1 is applied. Accordingly, when aplurality of CCs is aggregated and have a nested relationship, thetiming setting process of embodiment 1 can be simplified.

Specifically, embodiment 1 can be applied to CA combinations (CA ofUD-cfgs #1 and #3, CA of UD-cfgs #2 and #3 and CA of UD-cfgs #2 and #4)corresponding to shaded parts of FIG. 19 and the proposed methoddescribed below can be applied to the other CA combinations.

ACK/NACK Timing—Method 2-1

-   -   ACK/NACK for DL data received through the PCC        -   ACK/NACK timing configured for the PCC can be applied.    -   ACK/NACK for DL data received through the SCC        -   ACK/NACK timing (i.e. “common ACK/NACK timing”) configured            for one of the PCC and SCC, which has a smaller number of Us            (equivalently, a larger number of Ds) can be applied.            -   Preferably, only ACK/NACK timing of D having the same SF                timing as D of the SCC in UD-cfg of the selected CC can                be extracted and applied.    -   The common ACK/NACK timing can be commonly applied to all DL        data received through the PCC and SCC.

UG or PHICH Timing—Method 2-2

-   -   UG or PHICH for UL data transmitted through an MCC        -   UG or PHICH timing of the MCC can be applied.    -   UG or PHICH for UL data transmitted through an SCC        -   UG or PHICH timing (i.e. “common UG or PHICH timing”)            configured for one of the MCC and SCC, which has a larger            number of Us (equivalently, a smaller number of Ds) can be            applied.            -   Preferably, only UG or PHICH timing of U having the same                SF timing as U of the SCC in UD-cfg of the selected CC                can be extracted and applied.    -   The common UG or PHICH timing can be commonly applied to all DL        data received through the MCC and SCC.

Embodiment 3 Signal Transmission/Reception Timing and UL HARQ Process

As described above with reference to Table 8, the number of UL SFs isdefined differently according to UL-DL configuration in case of TDD, andthe number of UL HARQ processes and a UL HARQ RTT based on the number ofUL SFs can be configured differently according to UL-DL configuration.

When the UG or PHICH timing allocation schemes of embodiments 1 and 2are applied, in a specific combination of MCC/SCC, UG or PHICH timing ofUD-cfg having a UL HARQ RTT different from a UL HARQ RTT configured forthe MCC/SCC may be applied. For example, if the MCC corresponds toUD-cfg #6 and the SCC corresponds to UD-cfg #1 (having a UL HARQ RTT of10 SFs or 10 ms), UG or PHICH timing and a UL HARQ RTT (which is not 10SFs or 10 ms) configured for UD-cfg #6 are applied to SCC U when theproposed methods of embodiments 1 and 2 are applied, and thus a problemmay occur in configuring the entire UL HARQ timing.

FIG. 20 illustrates CA combinations in which a problem occurs inconfiguring UL HARQ timing, when UG or PHICH timing allocation schemesof embodiments 1 and 2 are applied. In FIG. 20, shaded parts correspondto CA combinations in which a problem occurs in configuring UL HARQtiming. An MCC/SCC combination corresponding to a shaded part is called“non-applicable MCC/SCC-comb”. Other MCC/SCC combinations are called anapplicable MS-comb. FIG. 20(a) shows a case in which UG or PHICH timingof the MCC is applied to the MCC and common UG or PHICH timing isapplied to the SCC. FIG. 20(b) shows a case in which common UG or PHICHtiming is applied to both the MCC and SCC.

Accordingly, the above-described UG or PHICH timing setting method isapplied to the applicable MS-comb and the following method can beconsidered for the non-applicable MS-comb.

0) While UG or PHICH timing setting methods of embodiments 1 and 2 areapplied, the UL HARQ RTT is changed to N*10 SFs or N*10 ms (N being aninteger greater than 1, preferably 1 or 2) on the basis of the followingmethod 3-0 or 3-0-1 only for a CC to which common UG or PHICH timing isapplied,

1) cross-CC scheduling may not be permitted (for both DL and UL or onlyfor UL),

2) carrier aggregation may not be permitted (for both DL and UL or onlyfor UL),

3) UL data scheduling/transmission for a corresponding SCC may beskipped or dropped when cross-CC scheduling is configured,

4) a UG or PHICH timing setting scheme based on the following method 3-1may be applied, or

5) a UG or PHICH timing setting scheme based on the following method 3-2may be applied.

HARQ Process Configuration—Method 3-0

-   -   UG/PHICH=>PUSCH timing relation (a time difference therebetween        is referred to as K SFs or K ms for convenience) can follow the        UG or PHICH timing of embodiments 1 and 2.    -   PUSCH=>PHICH/UG timing relation (a time difference therebetween        is referred to as L SFs or L ms for convenience) can be        configured such that a time required for        UG/PHICH=>PUSCH=>UG/PHICH corresponds to N*10 SFs or N*10 ms.        Here, N is an integer equal to or greater than 1, preferably, 1        or 2.        -   That is, L can be configured as N*10−K.

HARQ Process Configuration—Method 3-0-1

-   -   UG=>PUSCH timing relation (a time difference therebetween is        referred to as K SFs or K ms for convenience) can be configured        by applying the common UG or PHICH timing of embodiments 1 and 2        to PUSCH transmission in SF #n.    -   PUSCH=>PHICH timing relation (a time difference therebetween is        referred to as L SFs or L ms for convenience) can be configured        by applying the common UG or PHICH timing of embodiments 1 and 2        to PUSCH transmission in SF #n.    -   Finally, PHICH=>UG timing can be configured such that PUSCH        transmission at an interval of N*10 SFs or N*10 ms configures a        same PUSCH HARQ process. That is, the time difference between a        PHICH and a UG can be configured as H=N*10−K−L (instead of 0).

For example, a PUSCH in SF #N, a PHICH in SF #(n+L), a UG in SF#(n+L+(N*10−K−L))=SF #(n+N*10−K), and a PUSCH in SF #(n+N*10−K+K)=SF#(n+N*10) can be allocated such that they configure the same PUSCH HARQprocess.

Accordingly, in a view of PUSCH transmission, the UE can receive a PHICHin an MCC corresponding to SF#(n−K−(N*10−K−L))=#(n−K−H)=#(n−L)=#(n−(N*10−L)) and/or transmit a PUSCHin an SCC corresponding to SF #n when a UL grant is received in an MCCcorresponding to SF #(n−K). Whether the PUSCH is initially transmittedor retransmitted can be determined according to reception/non-receptionof the PHICH, content of the UL grant (e.g. whether an NDI (New DataIndicator is toggled).

For reference, applications of Method 3-0-1 are described. When DU-cfg#6 is determined as UL union according to the UG or PHICH timing settingschemes based on embodiments 1 and 2, UL grant/PHICH timing based on 20[TTI] UL HARQ RTT for PUSCH transmission in SF #3 can be configured withreference to Tables 5, 6 and 7 as follows. The unit of TTI may be SF orms.

-   -   UL=>PUSCH timing relation, that is, a time interval K [TTI] can        be determined by applying UL union timing, that is, UL        grant/PHICH timing configured for UD-cfg #6 to PUSCH        transmission in SF #3.    -   Referring to Table 5, a timing difference between a UL grant in        SF #6 and a PUSCH in SF #(10+3) corresponds to L=7 [TTI].    -   PUSCH=>PHICH timing relation, that is, a time interval L [TTI]        can be determined by applying UL union timing, that is, UL        grant/PHICH timing configured for UD-cfg #6 to PUSCH        transmission in SF #3.    -   Referring to Table 7, a timing difference between a PHICH in SF        #3 and a PHICH in SF #9 corresponds to L=6 [TTI].    -   PHICH=>UL grant timing relation, that is, a time interval 20−K−L        [TTI] can be determined such that PUSCH transmissions in SF #3        at intervals of 20 [TTI] configure the same PUSCH HARQ process.    -   PHICH=>UL grant timing interval becomes 20−K−L=20−7−6=7 [TTI]        according to the above results.    -   Consequently, the PUSCH in SF #3, the PHICH in SF #(3+L)=SF #9,        a UL grant in SF #(9+(20−K−L))=SF #16, a PUSCH in SF #(16+K)=SF        #23 can be allocated such that they configure the same PUSCH        HARQ process.

HARQ Process Configuration—Method 3-1

-   -   UG or PHICH for PUSCH transmission in MCC U    -   UG or PHICH timing of an MCC can be applied.    -   UG or PHICH for PUSCH transmission in SCC U (i.e. SF #n)    -   UG timing (hereinafter, SF #UG): this can be configured as a D        of an MCC closest to SF #(n−p) or SF #n present prior to SF        #(n−p). Here, p is an integer equal to or greater than 1,        preferably, 4.    -   PHICH timing (hereinafter, SF #PH): this can be configured as a        D of an MCC corresponding to a time after N*10 SFs or N*10 ms        from UG timing, that is, SF #(UG+N*10).    -   In case of n−UG>10−p (e.g. 6): synchronous HARQ having a HARQ        RTT of 10 SFs or 10 ms cannot be supported for an SCC U        corresponding to SF #n because PH−n<p (e.g. 4). Accordingly, the        following scheme can be considered for the SCC U.

Alt 0) Method 3-0, 3-0-1 or 3-2 can be applied.

Alt 1) Synchronous HARQ having a HARQ RTT of 20 SFs or 20 ms can besupported by respectively configuring UG timing and PHICH timing to SF#UG and SF #(UG+20).

Alt 2) Only the UG timing is configured as SF #UG (that is, PHICH timingis not configured) and SF #n can be used for one-time PUSCHscheduling/transmission depending only on an instantaneous UG (withoutan accompanying a PHICH based HARQ process). Here, one-time PHICHtransmission serves to perform only UL grant based (adaptive)retransmission without non-adaptive retransmission, which involves aHARQ process without a PHICH. For example, one-time PUSCH transmissioncan be used to carry UL data and/or UCI (e.g. ACK/NACK and/or CQI/PMI/R,etc.) (which do not involve a PHICH based HARQ process).

Alt 3) PUSCH scheduling/transmission for the SCC U corresponding to SF#n can be limited and the SCC U corresponding to SF #n can be used forother purposes (e.g. PUCCH and/or SRS and/or PRACH transmission).

HARQ Process Configuration—Method 3-2

The UG or PHICH timing setting methods (e.g. UL union) of embodiments 1and 2 are applied only to a CC (e.g. SCC) to which the common UG orPHICH timing is applied such that UL data transmission in an SCC D or Scan be skipped when the SCC D or S is included in a plurality of UL SFtimings that one UL HARQ process uses while hopping. To achieve this, itis possible to omit UG (and/or PHICH) scheduling/reception for UL datatransmission in an MCC DL SF (transmitting a UG that schedules a PUSCHat corresponding SF timing and ACK/NACK (PHICH) for the PUSCH at thecorresponding SF timing) corresponding to the SCC D or S.

That is, a plurality of SCC UL timings that a UL HARQ process uses whilehopping is connected on the basis of UL union timing, and transmissionof data (e.g. PUSCH) and transmission and reception of controlinformation (e.g. PHICH/UG) relating thereto at a UL timing that doesnot correspond to the SCC can be skipped (on UL union timing). When thecontrol information is skipped, connection of SCC ULs in a UL HARQprocess may be performed using UL union PHICH timing corresponding toprevious SCC UL and UL union UG timing corresponding to the followingSCC UL (here, the previous and following SCC ULs may not be contiguousin terms of UL union (HARQ) timing). For example, HARQ processes can beconnected in the order of SCC PUSCH transmission in the previous SCCUL=>PHICH reception at UL union PHICH timing corresponding to theprevious SCC UL (MCC)=>UL grant reception at UL union UL grant timingcorresponding to the following SCC UL (MCC)=>SCC PUSCH transmission inthe following SCC UL (here, PHICH/UL grant scheduling/reception for ULin a UL union between the previous SCC UL and the following SCC UL isomitted). In other cases (i.e. when the above-mentioned skippingoperation is not present), connection of SCC ULs in a UL HARQ processmay be performed using PHICH timing for previous UL in the UL union andUG timing that schedules the following UL in the UL union. Here, theprevious and following ULs may be contiguous in terms of UL union (HARQ)timing. For example, HARQ processes can be connected in the order of SCCPUSCH transmission in the previous UL in UL union=>PHICH reception atPHICH timing corresponding to the previous UL in the UL union (MCC)=>ULgrant reception at UL grant timing corresponding to the following UL inthe UL union (MCC)=>SCC PUSCH transmission in the following UL in the ULunion. Here, the previous and following SCC ULs are contiguous in termsof UL union (HARQ) timing, and thus PHICH/UL grant scheduling/receptionrelating to the previous and following SCC ULs is not omitted.

That is, UL grant or PHICH timing (i.e. UL union timing) defined inUD-cfg corresponding to a UL union of the MCC and SCC can be applied toperform PUSCH transmission (and PHICH/UL grant transmission) relating toa specific PUSCH HARQ process of the SCC over time. However, whenspecific PUSCH transmission timing (U1) defined in UD-cfg correspondingto the UL union is not defined as a UL SF in the SCC, PUSCH transmissionthat needs to be performed through U1 can be executed through the firstSCC UL SF (U2) available after U1. Here, it is assumed a UL SF (for theSCC) in which PUSCH transmission can be performed immediately before U1based on the UL union timing is U0. In this case, PUSCH HARQ relatedoperations can be performed in the order of PUSCH transmission in U0,PHICH reception at PHICH timing (D0) (at which ACK/NACK for a PUSCH istransmitted) with respect to transmission of the PUSCH in U0, UL grantreception at UL grant timing (D2) for scheduling a PUSCH in U2 and PUSCHtransmission in U2. Here, D0 and D2 may be identical or differentaccording to UL union timing. D2 may include D0 and may be defined as D2SF timing (e.g. UG timing) (valid in terms of UL union timing) closestto D0 after D0.

The method of the present embodiment is exemplified. If UD-cfg #6corresponds to an MCC and UD-cfg #1 corresponds to an SCC, SFs #2, #3,#4, #7 and #8 are UL SFs in case of the MCC and SFs #2, #3, #7 and #8are UL SFs in case of the SCC. Here, when the UL union method isapplied, a PUSCH HARQ process (i.e. UL grant/PUSCH/PHICH transmission)in the SCC can be performed at UL grant or PHICH timing defined inUD-cfg #6 (MCC). When Method 3-2 is applied to a specific PUSCH HARQprocess starting with initial PUSCH transmission in SF #3 of the SCC,the UE can perform the following operation based on UD-cfg #6 (MCC).

1) UL grant reception at UL grant timing (D0) for scheduling a PUSCH inSF #2

2) PUSCH transmission (initial transmission) in SF #2

3) PHICH reception at PHICH timing (D1) for PUSCH transmission in SF #2

UL grant reception at UL grant timing (D2) for scheduling a PUSCH in SF#13 (=#2+11(RTT))

Here, D1 and D2 may be the same SF timing.

4) PUSCH transmission (first transmission) in SF #13

5) PHICH reception at PHICH timing (D3) for PUSCH transmission in SF #13

6) UL grant reception at UL grant timing (D4) for scheduling a PUSCH inSF #27 (=#13+14(RTT))

Here, D3 and D4 may be the same SF timing or different SF timings. D4may include D3 and may be configured as D4 SF timing (valid in terms ofUL union timing) closest to D3 after D3.

When timing defined in UD-cfg #6 corresponding to a UL union is applied,retransmission of a PUSCH in SF #13 can be performed in SF #24. However,since a DL or S SF instead of a UL SF is defined in the SCC in case ofSF #24, PUSCH transmission in SF #24, reception of a UL grant thatschedules the PUSCH transmission, and PHICH reception with respect tothe PUSCH transmission can be omitted and retransmission of the PUSCH inSF #13 can be performed through SF #27 corresponding to the first SCC ULSF available after SF #24 according to the proposed method.

7) PUSCH transmission (second transmission) in SF #27 (=#13+14(RTT))

8) PHICH reception at PHICH timing (D5) for PUSCH transmission in SF #27

UL grant reception at UL grant timing (D6) for scheduling a PUSCH in SF#38 (=#27+11(RTT))

Here, D5 and D6 may be the same SF timing

9) PUSCH transmission (third transmission) in SF #38

10) PHICH reception at PHICH timing (D7) for PUSCH transmission in SF#38

UL grant reception at UL grant timing (D8) for scheduling a PUSCH in SF#52 (=#38+14(RTT))

Here, D7 and D8 may be the same SF timing

The above-described example will now be explained in more detail.

-   -   When UL HARQ timing defined in UD-cfg #6 corresponding to a UL        union is applied to an SCC, the following UL HARQ process for an        SCC PUSCH can be expected.

SF #2: PUSCH=>SF #6: PHICH+UG=>SF #13: PUSCH=>SF #19: PHICH+UG=>SF #24:PUSCH (invalid on SCC)=>SF #30: PHICH+UG=>SF #37: PUSCH=>SF #41:PHICH+UG=>SF #48: PUSCH=>SF #55: PHICH+UG=>SF #62: PUSCH

-   -   However, SF #24 cannot be used for SCC PUSCH transmission        because SCC (UD-cfg #1) corresponds to DL in SF #24.        Accordingly, UL HARQ timing can be determined as follows when        Method 3-2 is applied to the SCC.

SF #2: PUSCH=>SF #6: PHICH+UG=>SF #13: PUSCH=>SF #19: PHICH=>SF #20:UG=>SF #27: PUSCH=>SF #31: PHICH+UG=>SF #38: PUSCH=>SF #45: PHICH+UG=>SF#52: PUSCH

FIGS. 21 to 25 illustrate UG/PHICH timing with respect to SCC U (whichcan support 10-SF synchronous HARQ) calculated through Method 3-1according to UD-cfg of an MCC and UD-cfg of an SCC. FIGS. 21 to 25respectively show cases in which UD-cfg of the MCC corresponds to #0,#1, #2, #3 and #6. In the figures, numeral k configured for SF #m meansthat UG/PHICH timing for a PUSCH transmitted through an SCC U in SF#(m+k) is configured to D of the MCC in SF #m.

Only FIGS. 21 and 24 are described because FIGS. 21 to 25 illustrate thesame or similar schemes. Referring to FIG. 21, when the MCC correspondsto UD-cfg #0 and the SCC corresponds to UD-cfg #6 (5 Us are present inSFs #2, #3, #4, #7 and #8), 10-SF RTT synchronous HARQ can be supportedonly for SCC Us (n−UG≦6) corresponding to SFs #2, #4 and #7 and Alts 0to 3 can be applied to SCC Us (n−UG>6) corresponding to SFs #3 and #8(by configuring MCC Ds of SFs #0, #1 and #6 as UG or PHICH timing).Referring to FIG. 24, when the MCC corresponds to UD-cfg #3 and the SCCcorresponds to UD-cfg #1 (4 Us are present in SFs #2, #3, #7 and #8),10-SF RTT synchronous HARQ can be supported only for SCC Us (n−UG≦6)corresponding to SFs #2, #3 and #7 and Alts 0 to 3 can be applied to anSCC U (n−UG>6) corresponding to SF #8 (by configuring MCC Ds of SFs #1,#8 and #9 as UG or PHICH timing).

When UG or PHICH timing is configured using Method 3-0, 3-0-1, 3-1 or3-2 (or other methods), a specific D (e.g. MCC-D1) of the MCC, which isnot configured to transmit a UG or PHICH when the MCC operates alone,can be configured as UG or PHICH timing for PUSCH transmission in aspecific U of the MCC/SCC. For convenience, a U of the MCC/SCCcorresponding to MCC-D1 configured as UG or PHICH timing is called anorphan U. Here, MCC-D1 can be identified with reference to Tables 1, 6and 7. In this case, the orphan U (or all Us of a CC including theorphan U) can be used for one-time PUSCH scheduling/transmissiondepending only on instantaneous UG (without involving a PHICH based HARQprocess). Here, one-time PUSCH transmission means, although a HARQprocess is accompanied without a PHICH, to perform only UL grant based(adaptive) retransmission without non-adaptive retransmission. Forexample, one-time PUSCH transmission can be used to carry UL data and/orUCI (e.g. ACK/NACK and/or CQI/PMI/RI, etc.) (which do not involve aPHICH based HARQ process). Otherwise, a scheme of limiting PUSCHscheduling/transmission for the orphan U (or all Us of the CC includingthe orphan U) and using the orphan U for other purposes (e.g. PUCCHand/or SRS and/or PRACH transmission) can be considered. In this case,the UE can omit a procedure (e.g. search space monitoring and blinddecoding of PDCCH candidates) for receiving a UL grant DCI format in theD of the MCC, which corresponds to the orphan U.

Embodiment 4 Signal Transmission and Reception Timing and UL HARQProcess

The UL HARQ process configuration scheme of embodiment 3 processesnon-applicable MS-comb on the assumption that embodiments 1 and 2 areapplied. In the present embodiment, a generalized UL HARQ processconfiguration scheme that can be applied irrespective of CC combination(i.e. UD-cfg) is described. The following method can be considered.

HARQ Process Configuration—Method 4-1

-   -   UG or PHICH for PUSCH transmission in MCC U        -   UG or PHICH timing of an MCC can be applied.    -   UG or PHICH for PUSCH transmission in SCC U (i.e. SF #n)        -   UG timing (hereinafter, SF #UG): this can be set to a D of            an MCC closest to SF #(n−p) or SF #n present prior to SF            #(n−p). Here, p is an integer greater than 1, preferably, 4.        -   PHICH timing (hereinafter, SF #PH): this can be configured            as a D of an MCC corresponding to a time after N*10 SFs or            N*10 ms from UG timing, that is, SF #(UG+N*10). Here, N is            an integer equal to or greater than 1. For example, N can be            1.        -   In case of n−UG>10−p (e.g. 6): synchronous HARQ having a            HARQ RTT of 10 SFs or 10 ms cannot be supported for an SCC U            corresponding to SF #n because PH−n<p (e.g. 4). Accordingly,            the following scheme can be considered for the SCC U.

Alt 1) Synchronous HARQ having a HARQ RTT of 20 SFs or 20 ms can besupported by respectively configuring UG timing and PHICH timing to SF#UG and SF #(UG+20).

Alt 2) Only the UG timing is configured as SF #UG (that is, PHICH timingis not configured) and SF #n can be used for one-time PUSCHscheduling/transmission depending only on an instantaneous UG (withoutan accompanying a PHICH based HARQ process). Here, one-time PHICHtransmission serves to perform only UL grant based (adaptive)retransmission without non-adaptive retransmission, which involves aHARQ process without a PHICH. For example, one-time PUSCH transmissioncan be used to carry UL data and/or UCI (e.g. ACK/NACK and/or CQI/PMI/R,etc.) (which do not involve a PHICH based HARQ process).

Alt 3) PUSCH scheduling/transmission for the SCC U corresponding to SF#n can be limited and the SCC U corresponding to SF #n can be used forother purposes (e.g. PUCCH and/or SRS and/or PRACH transmission).

The following exceptions can be defined for the above-described ruleconsidering that HARQ RTT of UD-cfgs #0 and #6 is not 10 SFs or 10 ms.

-   -   When the MCC corresponds to UD-cfgs #1 to #6 and the SCC        corresponds to UD-cfg #0, UG or PHICH timing and UL HARQ RTT        configured for the SCC can be used.    -   When the MCC corresponds to UD-cfgs #1 to #5 and the SCC        corresponds to UD-cfg #6, UG or PHICH timing and UL HARQ RTT        configured for the SCC can be used.

FIG. 26 illustrates UG/PHICH timing with respect to SCC U calculatedthrough Method 4-1 according to UD-cfg of an MCC and UD-cfg of an SCC.In FIG. 26, numeral k configured for SF #m means that UG/PHICH timingfor a PUSCH transmitted through an SCC U in SF #(m+k) is configured to Dof the MCC in SF #m. FIG. 27 illustrates SCC Us (denoted by “0”) whichcan support 10-SF synchronous HARQ when UG/PHICH timing of FIG. 26 isemployed.

Referring to FIGS. 26 and 27, when the MCC corresponds to UD-cfg #3 andthe SCC corresponds to UD-cfg #1 (4 Us are present in SFs #2, #3, #7 and#8), 10-SF RTT synchronous HARQ can be supported only for SCC Uscorresponding to SFs #2, #3 and #7 and Alts 1 to 3 can be applied to SCCU corresponding to SF #8 (by configuring MCC Ds corresponding to SFs #1,#8 and #9 as UG or PHICH timing). Alternatively, when the MCCcorresponds to UD-cfg #3 and the SCC corresponds to UD-cfg #0 or #6, UGor PHICH timing and UL HARQ RTT configured for the SCC can be applied toSCC Us. Alternatively, when the MCC corresponds to UD-cfg #0 and the SCCcorresponds to UD-cfg #6 (5 Us are present in SFs #2, #3, #4, #7 and#8), 10-SF RTT synchronous HARQ can be supported only for SCC Uscorresponding to SFs #2, #4 and #7 and Alts 1 to 3 can be applied to SCCUs corresponding to SFs #3 and #8 (by configuring MCC Ds correspondingto SFs #0, #1 and #6 as UG or PHICH timing).

HARQ Process Configuration—Method 4-2

Method 4-2 is based on the assumption that the UL HARQ RTT is N*10 SFsor N*10 ms for all SCCs irrespective of MCC. Here, N is an integer equalto or greater than 1. Accordingly, it is assumed that the UL HARQ RTT ofan SCC is changed to N*10 SFs or N*10 ms irrespective of MCC even whenthe SCC corresponds to UD-cfgs #0 and #6. In this case, the followingscheme can be considered.

-   -   UG or PHICH for PUSCH transmission in MCC U        -   UG or PHICH timing of an MCC can be applied.    -   UG or PHICH for PUSCH transmission in SCC U (i.e. SF #n)        -   UG timing (hereinafter, SF #UG): this can be configured as a            D of an MCC closest to SF #(n−p) or SF #n present prior to            SF #(n−p). Here, p is an integer greater than 1, preferably,            4.        -   PHICH timing (hereinafter, SF #PH): this can be configured            as a D of an MCC corresponding to a time after N*10 SFs or            N*10 ms from UG timing, that is, SF #(UG+N*10). Here, N is            an integer equal to or greater than 1. For example, N can be            1.        -   In case of n−UG>10−p (e.g. 6): synchronous HARQ having a            HARQ RTT of 10 SFs or 10 ms cannot be supported for an SCC U            corresponding to SF #n because PH−n<p (e.g. 4). Accordingly,            the following scheme can be considered for the SCC U.

Alt 1) Synchronous HARQ having a HARQ RTT of 20 SFs or 20 ms can besupported by respectively configuring UG timing and PHICH timing to SF#UG and SF #(UG+20).

Alt 2) Only the UG timing is configured as SF #UG (that is, PHICH timingis not configured) and SF #n can be used for one-time PUSCHscheduling/transmission depending only on an instantaneous UG (withoutan accompanying a PHICH based HARQ process). Here, one-time PHICHtransmission serves to perform only UL grant based (adaptive)retransmission without non-adaptive retransmission, which involves aHARQ process without a PHICH. For example, one-time PUSCH transmissioncan be used to carry UL data and/or UCI (e.g. ACK/NACK and/or CQI/PMI/R,etc.) (which do not involve a PHICH based HARQ process).

Alt 3) PUSCH scheduling/transmission for the SCC U corresponding to SF#n can be limited and the SCC U corresponding to SF #n can be used forother purposes (e.g. PUCCH and/or SRS and/or PRACH transmission).

FIG. 28 illustrates UG/PHICH timing with respect to SCC U calculatedthrough Method 4-2 according to UD-cfg of an MCC and UD-cfg of an SCC.In FIG. 28, numeral k configured for SF #m means that UG/PHICH timingfor a PUSCH transmitted through an SCC U in SF #(m+k) is configured to Dof the MCC in SF #m. FIG. 29 illustrates SCC Us (denoted by “O”) whichcan support 10-SF synchronous HARQ when UG/PHICH timing of FIG. 28 isemployed.

Referring to FIGS. 28 and 29, when the MCC corresponds to UD-cfg #1 andthe SCC corresponds to UD-cfg #6 (5 Us are present in SFs #2, #3, #4, #7and #8), 10-SF RTT synchronous HARQ can be supported for all SCC Us (byconfiguring MCC Ds corresponding to SFs #0, #1, #4, #5 and #6 as UG orPHICH timing). Alternatively, when the MCC corresponds to UD-cfg #6 andthe SCC corresponds to UD-cfg #0 (6 Us are present in SFs #2, #3, #4,#7, #8 and #9), 10-SF RTT synchronous HARQ can be supported only for SCCUs corresponding to SFs #2, #3, #4, #7 and #9 and Alts 1 to 3 can beapplied to SCC U corresponding to SF #8 (by configuring MCC Dscorresponding to SFs #0, #1, #5, #6 and #9 as UG or PHICH timing).

When UG or PHICH timing is configured using the above proposed method(or other methods), a specific D (e.g. MCC-D1) of the MCC, which is notconfigured to transmit a UG or PHICH when the MCC operates alone, can beconfigured as UG or PHICH timing for PUSCH transmission in a specific Uof the MCC/SCC. For convenience, a U of the MCC/SCC, which correspondsto MCC-D1 configured as UG or PHICH timing, is called an orphan U. Here,MCC-D1 can be identified with reference to Tables 1, 6 and 7. In thiscase, the orphan U (or all Us of a CC including the orphan U) can beused for one-time PUSCH scheduling/transmission depending only oninstantaneous UG (without involving a PHICH based HARQ process). Here,one-time PUSCH transmission means, although a HARQ process isaccompanied without a PHICH, to perform only UL grant based (adaptive)retransmission without non-adaptive retransmission. For example,one-time PUSCH transmission can be used to carry UL data and/or UCI(e.g. ACK/NACK and/or CQI/PMI/RI, etc.) (which do not involve a PHICHbased HARQ process). Otherwise, a scheme of limiting PUSCHscheduling/transmission for the orphan U (or all Us of the CC includingthe orphan U) and using the orphan U for other purposes (e.g. PUCCHand/or SRS and/or PRACH transmission) can be considered. In this case,the UE can omit a procedure (e.g. search space monitoring and blinddecoding of PDCCH candidates) for receiving a UL grant DCI format in theD of the MCC, which corresponds to the orphan U.

FIG. 30 illustrates a BS and a UE applicable to an embodiment of thepresent invention. When a wireless communication system includes arelay, communication is performed between a BS and the relay on abackhaul link and between the relay and a UE on an access link. The BSor UE shown in FIG. 16 can be replaced by a relay as necessary.

Referring to FIG. 30, an RF communication system includes a BS 110 and aUE 120. The BS 110 includes a processor 112, a memory 114 and an RF unit116. The processor 112 may be configured to implement the proceduresand/or methods proposed by the present invention. The memory 114 isconnected to the processor 112 and stores various types of informationrelating to operations of the processor 112. The RF unit 116 isconnected to the processor 112 and transmits and/or receives RF signals.The UE 120 includes a processor 122, a memory 124 and an RF unit 126.The processor 122 may be configured to implement the procedures and/ormethods proposed by the present invention. The memory 124 is connectedto the processor 122 and stores various types of information relating tooperations of the processor 122. The RF unit 126 is connected to theprocessor 122 and transmits and/or receives RF signals. The BS 110 andthe UE 120 may have a single antenna or multiple antennas.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim by asubsequent amendment after the application is filed.

In the embodiments of the present invention, a description is made,centering on a data transmission and reception relationship between a BSand a UE. In some cases, a specific operation described as performed bythe BS may be performed by an upper node of the BS. Namely, it isapparent that, in a network comprised of a plurality of network nodesincluding a BS, various operations performed for communication with anMS may be performed by the BS, or network nodes other than the BS. Theterm ‘eNB’ may be replaced with the term ‘fixed station’, ‘Node B’,‘Base Station (BS)’, ‘access point’, etc. The term ‘UE’ may be replacedwith the term ‘Mobile Station (MS)’, ‘Mobile Subscriber Station (MSS)’,‘mobile terminal’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communicationapparatuses such as a UE, a relay, a BS, etc.

1. A method for transmitting an uplink signal by a wireless device in a wireless communication system, the method comprising: configuring, by the wireless device, a primary cell of a first Time Division Duplex Uplink-Downlink (TDD UL-DL) configuration and a secondary cell of a second TDD UL-DL configuration different from the first TDD UL-DL configuration; and for one or more downlink data on the secondary cell in subframe #n−k′ ((k′εK′), transmitting, by the wireless device, acknowledgement information about the one or more downlink data in subframe #n according to a reference TDD UL-DL configuration different from the second TDD UL-DL configuration, wherein K′ contains elements of K:{k₀, k₁, . . . , k_(M-1)} of the reference TDD UL-DL configuration such that subframe #n−k′ is a downlink subframe or a special subframe for the secondary cell, wherein K:{k₀, k₁, . . . , k_(M-1)} is defined in Table 1, and TDD UL-DL configurations are defined according to table 2: TABLE 1 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —

TABLE 2 Uplink- downlink config- Subframe number uration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

wherein D denotes a DL subframe, S denotes a special subframe and U denotes an UL subframe.
 2. The method of claim 1, wherein the reference TDD UL-DL configuration is a TDD UL-DL configuration whose DL subframe set includes both a DL subframe set of the first TDD UL-DL configuration and a DL subframe set of the second TDD UL-DL configuration, and each DL subframe set includes DL subframes and one or more special subframe.
 3. The method of claim 1, wherein a relationship between the first TDD UL-DL configuration, the second TDD UL-DL configuration and the reference TDD UL-DL configuration is shown in Table 3 below: TABLE 3 the first UL-DL the second UL-DL the reference UL-DL configuration configuration configuration 1 0, 6 1 2 0, 1, 6 2 3 0, 6 3 4 0, 1, 3, 6 4 5 0, 1, 2, 3, 4, 6 5 6 0 6 1 3 4 3 1 4 3 2 5 2 3, 4 5 4 2 5


4. The method of claim 1, wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #4 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#1, #3) or (#3, #1), wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #5 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#2, #3), (#3, #2), (#2, #4) or (#4, #2).
 5. The method of claim 1, wherein the acknowledgement information is transmitted: (i) on the primary cell via a physical uplink control channel (PUCCH), or (ii) on the primary cell or the secondary cell via a physical uplink shared channel (PUSCH).
 6. A wireless device for use in a wireless communication system, the wireless device comprising: a receiver; a transmitter; and a processor operatively connected to the receiver and the transmitter, the processor configured to: configure a primary cell of a first Time Division Duplex Uplink-Downlink (TDD UL-DL) configuration and a secondary cell of a second TDD UL-DL configuration different from the first TDD UL-DL configuration; and for one or more downlink data on the secondary cell in subframe #n−k′ (k′εK′), transmit acknowledgement information about the one or more downlink data in subframe #n according to a reference TDD UL-DL configuration different from the second TDD UL-DL configuration, wherein K′ contains elements of K:{k₀, k₁, . . . , k_(M-1)} of the reference TDD UL-DL configuration such that subframe #n−k′ is a downlink subframe or a special subframe for the secondary cell, wherein K:{k₀, k₁, . . . , k_(M-1)} is defined in Table 1, and TDD UL-DL configurations are defined according to table 2: TABLE 1 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —

TABLE 2 Uplink- downlink config- Subframe number uration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

wherein D denotes a DL subframe, S denotes a special subframe and U denotes an UL subframe.
 7. The wireless device of claim 6, wherein the reference TDD UL-DL configuration is a TDD UL-DL configuration whose DL subframe set includes both a DL subframe set of the first TDD UL-DL configuration and a DL subframe set of the second TDD UL-DL configuration, and each DL subframe set includes DL subframes and one or more special subframe.
 8. The wireless device of claim 6, wherein a relationship between the first TDD UL-DL configuration, the second TDD UL-DL configuration and the reference TDD UL-DL configuration is shown in Table 3 below: TABLE 3 the first UL-DL the second UL-DL the reference UL-DL configuration configuration configuration 1 0, 6 1 2 0, 1, 6 2 3 0, 6 3 4 0, 1, 3, 6 4 5 0, 1, 2, 3, 4, 6 5 6 0 6 1 3 4 3 1 4 3 2 5 2 3, 4 5 4 2 5


9. The wireless device of claim 6, wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #4 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#1, #3) or (#3, #1), wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #5 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#2, #3), (#3, #2), (#2, #4) or (#4, #2).
 10. The wireless device of claim 6, wherein the acknowledgement information is transmitted: (i) on the primary cell via a physical uplink control channel (PUCCH), or (ii) on the primary cell or the secondary cell via a physical uplink shared channel (PUSCH).
 11. A method for receiving an uplink signal by a wireless device in a wireless communication system, the method comprising: configuring, by the wireless device, a primary cell of a first Time Division Duplex Uplink-Downlink (TDD UL-DL) configuration and a secondary cell of a second TDD UL-DL configuration different from the first TDD UL-DL configuration; and for one or more downlink data on the secondary cell in subframe #n−k′ (k′εK′), receiving, by the wireless device, acknowledgement information about the one or more downlink data in subframe #n according to a reference TDD UL-DL configuration different from the second TDD UL-DL configuration, wherein K′ contains elements of K:{k₀, k₁, . . . , k_(M-1)} of the reference TDD UL-DL configuration such that subframe #n−k′ is a downlink subframe or a special subframe for the secondary cell, wherein K:{k₀, k₁, . . . , k_(M-1)} is defined in Table 1, and TDD UL-DL configurations are defined according to table 2: TABLE 1 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —

TABLE 2 Uplink- downlink config- Subframe number uration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

wherein D denotes a DL subframe, S denotes a special subframe and U denotes an UL subframe.
 12. The method of claim 11, wherein the reference TDD UL-DL configuration is a TDD UL-DL configuration whose DL subframe set includes both a DL subframe set of the first TDD UL-DL configuration and a DL subframe set of the second TDD UL-DL configuration, and each DL subframe set includes DL subframes and one or more special subframe.
 13. The method of claim 11, wherein a relationship between the first TDD UL-DL configuration, the second TDD UL-DL configuration and the reference TDD UL-DL configuration is shown in Table 3 below: TABLE 3 the first UL-DL the second UL-DL the reference UL-DL configuration configuration configuration 1 0, 6 1 2 0, 1, 6 2 3 0, 6 3 4 0, 1, 3, 6 4 5 0, 1, 2, 3, 4, 6 5 6 0 6 1 3 4 3 1 4 3 2 5 2 3, 4 5 4 2 5


14. The method of claim 11, wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #4 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#1, #3) or (#3, #1), wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #5 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#2, #3), (#3, #2), (#2, #4) or (#4, #2).
 15. The method of claim 11, wherein the acknowledgement information is received: (i) on the primary cell via a physical uplink control channel (PUCCH), or (ii) on the primary cell or the secondary cell via a physical uplink shared channel (PUSCH).
 16. A wireless device for use in a wireless communication system, the wireless device comprising: a receiver; a transmitter; and a processor operatively connected to the receiver and the transmitter, the processor configured to: configure a primary cell of a first Time Division Duplex Uplink-Downlink (TDD UL-DL) configuration and a secondary cell of a second TDD UL-DL configuration different from the first TDD UL-DL configuration; and for one or more downlink data on the secondary cell in subframe #n−k′ (k′εK′), receive acknowledgement information about the one or more downlink data in subframe #n according to a reference TDD UL-DL configuration different from the second TDD UL-DL configuration, wherein K′ contains elements of K:{k₀, k₁, . . . , k_(M-1)} of the reference TDD UL-DL configuration such that subframe #n−k′ is a downlink subframe or a special subframe for the secondary cell, wherein K:{k₀, k₁, . . . , k_(M-1)} is defined in Table 1, and TDD UL-DL configurations are defined according to table 2: TABLE 1 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —

TABLE 2 Uplink- downlink config- Subframe number uration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D

wherein D denotes a DL subframe, S denotes a special subframe and U denotes an UL subframe.
 17. The wireless device of claim 16, wherein the reference TDD UL-DL configuration is a TDD UL-DL configuration whose DL subframe set includes both a DL subframe set of the first TDD UL-DL configuration and a DL subframe set of the second TDD UL-DL configuration, and each DL subframe set includes DL subframes and one or more special subframe.
 18. The wireless device of claim 16, wherein a relationship between the first TDD UL-DL configuration, the second TDD UL-DL configuration and the reference TDD UL-DL configuration is shown in Table 3 below: TABLE 3 the first UL-DL the second UL-DL the reference UL-DL configuration configuration configuration 1 0, 6 1 2 0, 1, 6 2 3 0, 6 3 4 0, 1, 3, 6 4 5 0, 1, 2, 3, 4, 6 5 6 0 6 1 3 4 3 1 4 3 2 5 2 3, 4 5 4 2 5


19. The wireless device of claim 16, wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #4 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#1, #3) or (#3, #1), wherein the reference TDD UL-DL configuration is TDD UL-DL configuration #5 when (the first TDD UL-DL configuration, the second TDD UL-DL configuration) corresponds to (#2, #3), (#3, #2), (#2, #4) or (#4, #2).
 20. The wireless device of claim 16, wherein the acknowledgement information is received: (i) on the primary cell via a physical uplink control channel (PUCCH), or (ii) on the primary cell or the secondary cell via a physical uplink shared channel (PUSCH). 